(Full version) I, along with many of my friends and coworkers, have run into issues with maximizing Google Chrome windows on Mac OS X. It seems that, when clicking on the green button in the title bar, that the window resizes vertically, but not horizontally. And when you’re actually trying to get the window to fill up the full screen, this is highly unfortunate.

What’s going on

The green button is not the Maximize button in OS X; it’s the Zoom button. As described in Chrome’s issues tracker, Chrome’s intended behavior for this button is to “size-to-best-fit, not fill-screen”. Therefore, it will only make the window wider if there is some visible content on the page that’s wider than the window is currently, i.e., if there’s a horizontal scrollbar. This page shows it quite wonderfully: there’s a 65k-pixel-wide div at the bottom that will make the window expand to the full screen size when you Zoom. Hide the div, and the window will only expand vertically.

How to make Zoom fill the full screen

Despite this somewhat unexpected default behavior, there are a couple ways to fill the screen anyway when Zooming:

Press Shift when you click on the Zoom button. This, as implemented by Chrome, will make the window fill the full screen.

This one has some subtlety: Under System Preferences->Keyboard->Keyboard Shortcuts->Application Shortcuts, add a shortcut for Chrome. Make the Menu Title be “Zoom” (it’s under the Window menu). Since Command+M is the keyboard shortcut for Minimize, let’s make the Keyboard Shortcut for Zoom be Command+Shift+M. Go back to Chrome and try it out your keyboard shortcut. Voila! But wait–if you just click on Zoom in the menu, it will continue to resize only vertically. What’s going on here? Because you’re pressing Shift while activating Zoom with the keyboard shortcut, it works just like pressing Shift while clicking the green button. No joke.